Vehicle suspension system



Sept. 1, 1959 B. D. Mc N 2,902,274

I VEHICLE SUSPENSION SYSTEM Filed Feb. 21, 1958 INVENTO ZrauwerJ17I1ryre BY j Z42 away/ United States Patent VEHICLE SUSPENSION SYSTEMBrouwer D. McIntyre, Monroe, Mich., assignor to Monroe Auto EquipmentCompany Application February 21, 1958, Serial No. 716,690

2 Claims. (Cl. 267-8) This invention relates generally to a vehiclesuspension system and more porticularly to auxiliary suspension devicesadapted to be used, for example, on vehicles in conjunction with vehiclemain springs so as to provide improved suspension characteristics when avehicle is both lightly loaded and heavily loaded, and constitutes animprovement over the structure shown in the copending application ofBrouwer D. McIntyre and William D. McIntyre, Serial No. 665,001, filedJune 11, 1957, now Patent No. 2,874,955, granted Feb. 24, 1959, entitledVehicle Suspension System.

While the auxiliary suspension devices shown in the aforementionedcopending application have been highly successful and hundreds ofthousands of such devices have been sold, it has been noted that whenthe devices are installed on an automobile, the back end of theautomobile body is raised a few inches higher than normal, when theautomobile is empty or lightly loaded. While this has not proven to be aserious problem, some people feel that this is undesirable from anappearance standpoint and would prefer a suspension having the samedesirable load carrying characteristics without raising the back end ofthe automobile body more than a nominal amount, when the automobile isempty or lightly loaded.

it is, therefore, an object of this invention to provide improvedauxiliary suspension devices which can be easily and quickly mounted ona vehicle in place of the rear shock absorbers and which will only raisethe height of the back end of the vehicle body a nominal amount when thevehicle is unloaded, while at the same time automatically leveling avehicle body for both light and heavy loads without upsetting thevehicle suspension system balance so that bottoming of the vehicle frameand rear axle and upward tilting of the vehicle headlights will be substantially eliminated without destroying the comfortable ridecharacteristics of the vehicle.

It is a still further object of this invention to provide a device ofthe aforementioned type which is relatively inexpensive to manufacture,efficient in operation and durable in construction.

These and other objects of this invention will become apparent from thefollowing detailed description taken in conjunction with theaccompanying drawing in which:

Figure 1 is a rear elevational view of a'vehicle partially broken awayin section and in phantom, showing the sus pension system of thisinvention,

Fig. 2 is a sectional view .of an auxiliary suspension device of thisinvention with the shock absorber and springs shown in their compressedposition,

Fig. 3 is a view, partially in section and partially in ice elevation ofthe suspension device illustrated in Fig. 2 and showing the relativeposition of the springs and shock absorber when the shock absorber is inan extended position, and

Fig. 4 is a fragmentary sectional view of the structure illustrated inFig. 1 taken along the line 44 thereof.

Referring now to the drawing, it will be seen that a vehicle isillustrated having a body 5 and chassis frame 7, which includeslongitudinal members 9 and a lateral cross frame member 11, suspended atthe rear thereof on a rear axle 13 and ground engaging wheels 15 by leafsprings 17, adjacent each wheel 15. The springs 17 are connected bysuitable spring shackles, not shown, to the chassis frame and bysuitable bolt and bracket assemblies 19 to the housing of the axle 13.On conventional automotive vehicles, hydraulic direct acting tubularshock absorbers are provided adjacent each ofthe springs 17 and for thispurpose a stud or pin 21 is provided on the lateral cross frame member11 adjacent each wheel 15 and a suitable supporting bracket portion 23is provided on each spring bracket and bolt assembly 19. The oppositeends of the shock absorber are thus connected between the sprung andunsprung assemblies of the vehicle. The auxiliary suspension devices 25of this invention are mounted in place of the conventional shockabsorbers, adjacent the rear wheels of the vehicle, so as to provide anauxiliary rear suspension for the vehicle.

Each suspension device 25 incorporates a hydraulic tubular direct actingshock absorber 2 7 which includes a pressure cylinder 29 within which aported and valved piston assembly 31 is slidably supported. The lowerend of the pressure cylinder is closed by means of a base valve assembly33 which permits hydraulic fluid to flow between the pressure cylinderand a reservoir 35 provided between the pressure cylinder and a reservetube 37, Which concentrically surrounds the pressure cylinder in spacedrelationship therewith. A piston rod 39 is connected to the pistonassembly 31 and extends upwardly through a rod guide assembly 41 whichcloses the upper end of the pressure cylinder and through a sealassembly 43 which, in conjunction with a cap 45, closes the upper end ofthe reserve tube 37. The lower end of the reserve tube 37 is closed bymeans of an end cap or closure 47. The shock absorber piston assembly 31and base valve assembly 33 are both ported and valved as described indetail in the copending application, Serial No. 665,001, so as toproperly cooperate with the vehicle main and auxiliary suspensionsprings and thereby provide comfortable and desirable vehicle ridingcharacteristics under various load conditions.

Each suspension device has a stud type end fitting 49 on the lower endof the shock absorber which is connectible to the vehicle spring bracketportion 23 in the same manner as a conventional shock absorber, whilethe upper end of the piston rod 39 of each suspension device has aloop-type fitting 51 thereon which is adapted to be connected to a pin21 on the vehicle frame in the same manner as a conventional shockabsorber.

An annular shoulder or projection 53 is formed in the wall of thereserve tube 37 adjacent to, but above, the lower end thereof. Anannular rigid spring support member 55 is sleeved over the upper end ofthe shock absorber and abuts the annular'shoulder 53 ,on the reservetube. The spring support member 55 is provided with an annular flange 57on the lower end thereof which engages and supports the lower end of afirst coil spring 59. A rubber, fiber or plastic washer 61 is sleevedover the top of the shock absorber and engages the top surface of thespring support 55. An elongated tubular spacer 63 is sleeved over thetop of the shock absorber and rests upon the washer 61. The tubularsleeve 63 may be made of a suitable material such as rubber, fiber orplastic and the inner and outer walls thereof are corrugated at 65 and67 respectively. The inside corrugations permit air to flow between thereserve tube and the spacer 63 so that the shock absorber will beproperly cooled at all times, while the outer corrugations reducefriction between the spacer and a slidable sleeve-like support member 69which is sleeved over the top of the shock absorber and which has anannular flange 70, intermediate the ends thereof, which engages the topof the first coil spring 59. The spacer 63 acts not only as a slidesupport for the sleeve 69 but also co-operates in maintaining the coilsprings which surround the shock absorber in a concentric relationshipwith the reserve tube, and also prevents metal to metal contact betweenthe springs and the reserve tube.

A second coil spring 73 is sleeved over the top of the shock absorberand the lower end thereof engages the top of the annular flange 70 ofthe slidable sleeve support 69. The upper end of the second coil spring73 is connected with the piston rod 39 by means of a hat-shaped supportmember 74 which has its inner periphery connected with the piston rodand its lower or outer periphery engaged in an annular notch or groove75 formed in the upper end of a split collar or ring 76. The collar orring is split into halves and has a depending annular flange 77 on thelower end thereof which is adapted to engage the inner diameter of thecoil spring 73, at the upper end thereof, and the collar has ahorizontally disposed shoulder 78 immediately above the flange 77 whichengages the top of the coil spring 73. The split ring or collar 76 isinserted into engagement with the upper end of the spring 73 and withthe support 74 by compressing the spring slightly and slipping the twohalves into position separately. When both ring halves are in positionthe spring 73 is thereby unitarily assembled with the shock absorber 27so that an auxiliary suspension unit or device is provided which can bemounted on a vehicle as previously described.

It will likewise be appreciated that the unit may be easily disassembledin case of any damage or inoperative conditions simply by removing thetwo halves of the split ring 76 after compressing the springs 73 and 59slightly. Thereafter, the springs, spacers and supports can be easilyremoved.

The first coil spring 59 has a rate of the order of 20 pounds while thesecond coil spring '73 has a rate of the order of 60 to 80 pounds. Thefirst coil spring 59 is of a sufiicient length that it will keep the topof the second coil spring 73 in engagement with the split collar 76 evenwhen the shock absorber is fully extended as illustrated in Fig. 3. Itwill, however, be noted that when the unit is compressed, the lower endof the slidable sleeve support 69 engages the washer 61, which issupported on the spring support member 55, before the spring 59 is fullycompressed, thus providing a rigid support for the lower end of thespring 73 during additional compression of the spring 73.

Because the spring 59 is considerably lighter than the spring 73, itwill be at least partially compressed by the weight of the vehiclesprung assembly, even when the vehicle is not loaded by eitherpassengers or baggage or other merchandise. That is, the rate of spring59 is such that it will, when there are about two people in the vehicle, be compressed to the extent shown in Fig. 2. On the other hand,spring 73 will be only slightly compressed when the bottom of the sleeve69 first engages the spring support 55. Thereafter, as additional loadis put in the vehicle in the form of passengers, baggage or othermerchandise, the spring 73 will be additionally compressed.

Tests have shown that while the suspension devices shown in applicantsaforementioned copending patent application will increase the unloadedvehicle sprung assembly height one to two inches, the devices of thisinvention will only cause about /4 inch increase in height. Furthermore,the device of this invention will reduce deflection of the sprungassembly under heavy loads approximately 2200 pounds, about two inches,as compared to a standard vehicle not incorporating the devices of thisinvention. Thus, clearance between the axle and frame of a vehicle isincreased from about one inch to about three inches. Therefore, even atfull vehicle loads, the devices of this invention keep the vehicleheadlight beams on the road, materially reduce suspension bottoming,improve vision from the vehicle and improve the handling characteristicsof the vehicle. This is accomplished without adding harshness to theriding characteristics of the vehicle, even when lightly loaded, all asspecifically pointed out in applicants aforementioned copendingapplication.

What is claimed is:

1. In a suspension device, a hydraulic direct acting tubular shockabsorber including an elongated tubular pressure cylinder, abore-fitting piston slidably disposed in said pressure cylinder andadapted to control flow of hydraulic fluid therepast to opposite sidesthereof, a reserve tube concentrically surrounding said pressurecylinder in spaced relation thereto, valve means closing one end of saidpressure cylinder and communicating said pressure cylinder and saidreserve tube, means closing the end of said reserve tube adjacent saidpressure cylinder valve means, a piston rod connected with said pistonand projecting beyond the opposite ends of said pressure cylinder andreserve tube, closure means closing said opposite ends of said pressurecylinder and reserve tube and slidably receiving said piston rod, meanson said one end of said reserve tube and on the projecting end of saidpiston rod adapted to be connected with relatively movable assemblies, afirst coil spring sleeved over said reserve tube, an annular shoulderformed in the wall of said reserve tube adjacent said one end thereof, asupport member sleeved over said reserve tube and engaging said annularshoulder and one end of said first coil spring so as to support said oneend of said first coil spring on said reserve tube, a sleeve memberslidably disposed on said reserve tube, an annular flange formed on saidsleeve member intermediate the ends thereof and engaging the oppositeend of said first coil spring, one end of said sleeve member beingengageable with said support member when said first coil spring iscompressed and prior to full compression thereof, a second coil springsleeved over said reserve tube and having one end thereof engaging saidsleeve member flange, a split ringlike support engaging the opposite endof said second coil spring and removably connected with said piston rodadjacent the projecting end thereof so as to support the opposite end ofsaid second coil spring on said piston rod, said first coil springhaving a substantially lower spring rate than said second coil springand being of a substantially shorter length than said second coilspring, said first coil spring being of a length sufiicient to maintainsaid second coil spring in engagement with said split ring-like supportwhen said shock absorber is in its fully extended position.

2. In a suspension device, a hydraulic direct acting tubular shockabsorber having relatively movable telescopic parts, a first coil springdisposed substantially concentrically with respect to said shockabsorber, means on one of said shock absorber parts engaging andsupporting one end of said first coil spring, a second coil springdisposed concentrically with respect to said shock absorber, a supportmember slidably disposed on said one shock absorber part and engagingthe opposite end of said first spring and one end of said second spring,and means on the other of said shock absorber parts engaging theopposite end of said second spring, said support member being engageablewith said one shock absorber part spring supporting means when saidfirst coil spring is compressed a predetermined amount and prior to fullcompression thereof, said first coil spring having a substantially lowerspring rate than said second coil spring so that when a load is appliedto said device said slidable support member will engage said one shockabsorber part spring supporting means prior to any substantialcompression of said second spring, said first 6 spring being of asubstatnially shorter length than said second spring, said first springbeing of a length suflicient to maintain said second coil spring inengagement with said other shock absorber part spring supporting meanswhen said shock absorber is in its fully extended position.

References Cited in the file of this patent FOREIGN PATENTS

